COMPARISON OF SOUND ISOLATING EARPHONES AND NOISE-CANCELLING HEADPHONES

Comparison of Sound Isolating Earphones and Noise-Cancelling Headphones

Comparison of Sound Isolating Earphones and Noise-Cancelling Headphones

Background

In the following paragraphs we will show you that in-ear earphones isolate up to 44 decibels compared to only 26 decibels with noise cancelling full size headphones such as Bose QC 3 Quiet Comfort. We also know that in-ear earphones listed on this page are capable of handling from humming airplane engines to babies' crying while noise cancelling headphones cannot cancel out higher frequency sounds such as a baby crying on an airplane. Having said that, if you really want a full size noise cancelling headphone such as Bose, please visit our other website Headphone Solutions for: The Best Full-Size Noise Canceling Headphones Showdown.

As portable audio devices become increasingly common, people are often listening in noisy environments. A variety of headphone products on the market reduce the level of background noise heard by the listener, but with varying effectiveness. To learn more about how these products differ in performance, Shure commissioned a research study to compare the noise-reducing performance of its sound isolating earphones to competitive headphones that utilize Active Noise Cancellation (generically referred to as Active Noise Reduction in the study). How these two different technologies work?
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How These Technologies Work

Sound isolating earphones prevent noise from entering the ear naturally. A foam, rubber, or plastic sleeve surrounding the earphone allows it to fit into the ear instead of resting outside of it. The snug fit and unique acoustic properties of the sleeve prevents outside noise from entering the ear. Sound isolating earphones do not require circuitry or batteries. Noise-cancelling headphones use electronic circuitry to remove noise after it has entered the headphone earcup. Microphones inside each headphone earcup sample the noise field, and an electronic circuit creates an inverse or ‘mirror-image’ of the noise signal and adds it to the music. The actual noise and the inverse noise cancel each other out. The microphones and circuitry require batteries in order to operate.

Which Products Were Tested

The testing lab purchased two examples each of popular noise-cancelling headphones manufactured by Bose, Sony, and Sennheiser. These were compared to Shure E2c and Shure E3c sound isolating earphones equipped with various types of sleeves. To insure accuracy, ten subjects were tested with each product on three separate occasions. Shure personnel were not present during testing.

Testing Procedure

The goal of the tests was to measure the amount of noise reduction (referred to as Insertion Loss in the study report) provided by each product. The sound isolating earphones were tested using a method called Real Ear Attenuation Threshold (REAT), in which the test subjects identified the sound level (or ‘threshold’) at which they could no longer hear the test noise signal, both with and without the earphones in place. The difference between the two measurements is the noise reduction (Insertion Loss) provided by the earphones. The REAT test method cannot be used for headphones that use electronic circuitry to cancel noise, so an alternate method called Microphone in Real-Ear (MIRE) was used for the noise-canceling headphones. With this method, a very small measurement microphone was placed in each of the subject’s ears, and the noise level inside the ear with the noise cancellation electronics turned on was measured and compared to the noise level outside of the headphones.

Test Results

The amount of noise reduction provided by each product was measured in nine standard frequency bands across the audible spectrum. The results are expressed in decibels.

Interpreting The Test Data

The noise reduction performance of each product tested in the study is expressed in decibels at nine different points across the audible frequency spectrum. For easier comparison, Shure calculated a single average noise reduction figure for each product. These numbers represent the overall noise reduction that a user would experience. The average performance numbers were also converted into a noise reduction percentage (compared to not wearing any headphones at all). In addition, the relative performance difference between Shure sound isolating earphones and competitive noise-canceling headphones is stated as both a percentage improvement and a relative performance factor.

From Wikipedia

Canalphones (a.k.a. in-ear earphones, IEM) are generally believed to be safer than open-air headphones for use in noisy environments. The reason for this is that much of the external noise which is usually heard while using earphones or headphones is blocked out by canalphones, therefore allowing the user to listen at lower volume levels without having to turn up the listening device to compete with background noise. Canalphones are a passive counterpart to active noise canceling headphones, which use circuitry and destructive wave interference to attenuate sound. Canalphones (or in-ear earphones) may reach isolation levels of -30dB to -40dB, while noise canceling headphones isolate by a degree of -15dB to -20dB. Closed and noise canceling headphones can have a similar effect, although sound attenuation of the latter is usually limited in frequency range and amplitude: closed headphones do not isolate low frequency sounds very well, and noise cancelling headphones do not attempt to attenuate high frequency sounds.

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